In high-frequency and low-noise amplifiers, the following characteristics are required: noise in a high-frequency signal amplified and output is low, and the operation is stable from lower range to higher range outside an operation frequency bandwidth. For example, Patent Literature 1 discloses such a type of conventional amplifier whose circuit configuration includes a stabilizing circuit arranged between an input terminal and a gate side of a transistor. The stabilizing circuit includes: an LC series resonant circuit consisting of an inductor and a capacitor (its resonant frequency is equal to the frequency of a high-frequency signal from the input terminal); and a resistor connected in parallel with the resonant circuit. In this circuit configuration, the LC series resonant circuit functions as a band-pass filter that can reduce the transmission loss of a signal at the resonant frequency of the resonant circuit, whereas outside the range of the operation frequency (in lower and higher ranges), due to the influence of the resistor connected in parallel with the LC series resonant circuit, it is possible to increase the transmission loss. Consequently, stabilization can be achieved from lower to higher ranges outside the frequency bandwidth while a noise figure at the operation frequency is not deteriorated.